Crusher

ABSTRACT

Portable crusher system achieving high crushing efficiency with structural simplicity. In a preferred embodiment two side-by-side crushing bites or passes are operated using two adjacent rollers on a first shaft and two separate opposing rollers on their respective second and third shafts, all supported by the same frame. The bite spacings are individually adjustable. The entire crushed stream leaving each bite is screened, and material which is product-sized and smaller is removed therefrom before any of the crushed material is fed into another crushing cycle. Each bite receives only the sizes appropriate for its bite spacing.

United States Patent Stephanek 1 Mar. 7, 1972 CRUSHER Primary Examiner-Andrew R. Juhasz [72] Inventor. Roy W. Stephanek, Cedar Rap1ds, Iowa Assistant Examiner cary L Smith 73 Assignee: Pettibone Corporation, Chicago, 111. y- Robertson & Vandenburgh [22] Filed: Aug. 27, 1969 57 ABSTRACT [21] A 853M Portable crusher system achieving high crushing efficiency with structural simplicity. In a preferred embodiment two [52 us. c1. ..241/7s,241/97, 241/101 M, side-by-side crushing bites Passes are WWWi "sing 241/230 adjacent rollers on a first shaft and two separate opposing rol- 1511 Int. Cl. "mm 4/32, B07b 1/28 leis iiiei' msPecii"e and shafts 5s 1 FieldoISearch ..241/75, 81, 97 110 111 113 by the Same iiamc- The bite spacings are individually 241/120, 122 143444 223 230 ble. The entire crushed stream leaving each bite is screened, and material which is product-sized and smaller is removed [56] References Cited therefrom before any of the crushed material is fed into another crushing cycle. Each bite receives only the sizes ap- UNITED STATES PATENTS propriate for its bite spacing.

2,325,719 8/1943 Turner ..24l/l44 X 7 Claims, 4 Drawing Figures CRUSHER BACKGROUND OF THE INVENTION Several compound roll crushers have heretofore been extensively used or promoted. By compound is meant a crusher carried between one pair of side frames but having two passes or bites in the interest of economy of parts and conservation of space. Usually these have been arranged to provide two stages of crushing. The most obvious arrangement would be a first stage or coarse-crushing in a first bite, and a second stage or finer crushing then being performed by permitting the discharge passing out of the first bite to move directly to a second bite having a smaller bite-spacing.

One class of compound roll crusher has used three roll shafts, two being spaced about a central roll so that a given point on the surface of the central roll formed one bite with the second roll and then moved to form another bite with the third roll. The above-mentioned obvious two-staging was not efficient here because the amount of material which could pass the first large bite would not pass through the smaller bite. The first bite therefore could not be worked anywhere near its capacity. To reduce this inefficiency one three-shaft crusher promoted has reversed the order of the bites, the finer being first. The second bite, being larger, could pass more than the first, and so a second feed stream added more. However, it is apparent that much of the actual potential crushing capacity is lost in'such a system due to the fact that nearly all of the discharge from the first, finer, bite, being product-sized and smaller material is fed to the second bite, where it takes up room for no use. When one roll surface cooperates with two other rolls successively, it is not practical to remove the material after the first bite, so it must pass through the second bite.

There has also been very extensive use of compound roll crushers in which a plurality of crushing bites were established by four rollers, two mounted on each of a single pair of axles. Here, slightly different sized rollers have been utilized to provide desirable difference in spacing of the two bites to provide multiple-stage crushing. This had the great advantage (US. Pat. No. 2,325,719) that from each bite the material could go to a screen, and sized material be removed. One of the most serious shortcomings of the latter-mentioned systems is the inflexibility in relationship between the two bite-spacings. Increasing the gap between one of the rollers necessarily affects the gap between the other rollers.

It is an object of this invention to provide a crusher which achieves multiple stage-crushing, in which the spacing between crushing rollers at each stage is adjustable indepen dently of the other stages, and which permits greater utilization of the full crushing capacity of each of the bites. The independent adjustments can so divide the total crushing that neither bite does less than its share, and the arrangement permits elimination from the stream being fed to each particular roller pair of material too small to be crushed therebetween.

It is also an object of this invention to provide such a roll crusher system which is particularly adaptable and useful in a portable crusher.

SUMMARY OF THE INVENTION Highly efficient compact crushing structure includes a common, elongated main crushing roll forming bites with each of a plurality of shorter crushing rolls, the shorter opposing rolls being independently mounted and axially displaced so that they cooperate with the main roll respectively from its opposite ends to an intermediate point. The crusher plant includes a classification system, i.e., screening system, which screens an input stream, removing product-sized and smaller material from the stream, and discharging to each bite a stream including only sizes appropriate for that bite. All of the crushed material from each bite is recycled to the classification system prior to any subsequent pass of any portion of the processed material between crushing rolls.

DESIGNATION OF THE FIGURES FIG. 1 is a schematic perspective fragmentary view of a portable crusher in accordance with this invention, shown with some enclosure and framing members on the nearest side being removed or cut away for the purpose of clarity.

FIG. 2 is an elevational view taken approximately along the line 2-2 of FIG. 3.

FIG. 3 is a plan view of the crushing roll portion of a portable crusher in accordance with this invention.

FIG. 4 is a partially cross-sectional view taken approximately along the line 4-4 of FIG. 3.

RECIRCULATING SYSTEM This invention is illustrated as embodied in a portable rock crusher, plant 10, includes a frame 11, wheels 12, feeding hopper 13 for raw material 14, and product-discharge conveyor 15. All material 16 to be processed is carried to the screening or classification section 17 by elevator-conveyor 19. The screening section 17 is conventionally a set of screens in an oscillating frame. The conveyor 19 discharges onto scalping screen 21. Oversized material 23 is carried on chute 25 to jawcrusher 27. Material discharged from jawcrusher 27 is carried by recycle conveyor 29 to lift mechanism 31 which deposits recycled material 33 on elevator-conveyor 19. Thus, material 16, in the classification input stream includes recycled material 33 and raw material 14.

Material passing through scalping screen 21 is separated by size or classified by screens 35 and 37 respectively, said screens being of increasing fineness. The material retained on screens 35 and 37 is material which is larger than product specification size. Material remaining on screen 35 consists of larger particles or pieces than the material remaining on screen 37. Larger material 39 passing over screen 35 is fed by means of chute 40 to the coarse bite 42 between roll 44 and roll 45. Material 49 passing over the top of screen 37 passes by means of chute 50 to finish bite 52 between rolls 54 and 55. Rolls 44 and 54 may be two parts of a single roll. The material passing from the two bites 42 and 52 is discharged from each immediately by gravity onto recycle conveyor 29 for return by way of lift 31 and elevator-conveyor 19 to screening section 17. Most of the material from bite 52 will now pass through the entire screening section 17, Le, through screen 37, fall on chute 57 and be deflected to discharge conveyor 15. Most of the fines fall through the screens quickly and are discharged separately by conveyor 58.

ROLL-CRUSHER FEATURE In accordance with the illustrated embodiment of this invention the roll crusher, which embodies the main novelty of the invention comprises a pair of parallel framing members 69, (FIG. 3) which are Y-shaped as seen in FIG. 2. In the illustrated embodiment one of the branches 61, 61' is in a straight line with its respective trunk 62, 62'. The other branches 63, 63 of Y 69, are disposed upwardly at an angle, e.g., 45, from their respective horizontally disposed trunk portions 62, 62'.

Rolls or roll portions 44, 54 are carried by axle or shaft 64. Axle 64 rotates in bearing 65, which is fixed with respect to framing member 69. Axle 67 is fixed to roll 55 and rotates in bearings 68, 68'. Axle 70 is fixed to roll 45 and is supported by bearings 71.

The bearings 68, 68', 71, referred to immediately above, have substantially identical spring-loading, which may be described with reference to hearing 68. Adjusting screws 72 bear against plate 73 which in turn bears against coil springs 74, and this in turn bears against bearing means 68 which is slidably mounted between upper and lower members 76, 76 respectively of frame branch 61.

Shims 79 are added or removed from the space between bearing 68 and opposing surface 81 of frame, generally 69, and detennine the bite space in each instance. Hydraulic rams (not shown, because conventional) located in bumper block 84, aid in bite adjustment.

POWER TRAIN Axle 83, rotating on suitable bearings (not shown since conventional and not necessary for understanding of the invention) is connected by means of key slot 85 or other conventional means to the power source (not shown since not part of the novel aspects of the invention). Flywheel 87 is fixed to the other end of axle 83. In the illustrated embodiment, the rotation of axle 83 is transmitted to axle 64 by means of conventional gears or drive chain (not shown) enclosed within safety housing 89. Rubber-(pneumatic) tired wheels 91, 91 are mounted at the ends 92, 92' of axle 64 which extend exteriorly of frame member 69. Compressed against the circumferential surface of rubber-tired wheel 91 is rubber-tired wheel 93 which is mounted on an external end portion 94 of axle 70 and is fixed thereto. Compressed against the circumferential surface of wheel 91' is rubber-tired wheel 96 which is mounted to and fixed to an external end portion 97 of axle 67. The rubbertired wheels described immediately hereinbefore provide the transmission of power to crushing rolls 45 and 55. Upon rotation of power axle 83 all crushing rolls are power rotated.

SIGNIFICANT CONSIDERATIONS The mounting of rolls 45 and 55 on separate axles is of considerable significance. If both were mounted on the same axle, widening of the gap between one of these rolls and its opposing roll (either momentarily or by change of the fixed adjustment) would also affect the gap between the other set of rolls. For example, during the normal course of operation, it is entirely normal for either roll 45 or 55 to be forced away from the opposing roll 44, 54 due to the presence of a large object or piece therebetween that does not crush. In accordance with this invention each roll 45, 55 has its own gap between itself and the opposing roll and variation of the gap-spacing of one set has absolutely no effect on the gap-spacing between the other roll and its opposing roll.

Although transmission rubber-tired wheel 93, 96 could be at either end of the respective shafts, positioning each at that end of its respective axle which is furthest removed from its respective crushing roll may minimize the effect of momentary lateral motion of crushing rolls 45 and 55 respectively on the power transmission. Thus, whenever crushing roll 55 on axle 67 is momentarily moved away from crushing roll 54, the lateral motion of rubber-tired wheel 96 is substantially minimized since axle 67, as viewed from above, tends to swing or rock around the bearing more remote from roll 55 and nearest the rubber-tired wheel, namely bearing 68'. Thus, even though crushing roll 55 is being moved away from its opposing roll 54 due to the presence of large hard objects therebetween, power transmission wheels 96, 91' tend to remain in proper compressed contact with each other thus assuring continued power transmission to crushing roll 55.

It might seem to be strange and wasteful to use three long shafts sturdy enough not to be subject to disastrous flexing in the long span between the side frames, when two of them could be shortened and lightened if an intermediate frame were used. Nevertheless, it works out very satisfactorily, especially in a portable crusher plant subject to width restrictions when on highways so that optimum use of the width permitted is all important. Furthermore the heavy shafts are found to be actually more economical than any practical use of an intermediate frame.

It is noted that the streams of material 39 and 49 are not mixed while passing between the crushing rolls but rather each is fed only to a bite best suited to its particle size. It is further noted that any material being crushed only passes through the bite between one pair of rolls per pass through the system. The passing of material through one bite per pass has been found to greatly increase the capacity of the equipment considering its size.

One of thereasons for the increase in capacity afforded by this invention is the fact that crushed material is screened before being fed again into the bite between the same or another pair of crushing rolls. Thus, only that fraction of crushed material which requires further crushing is fed into one of the crushing bites, the other material being eliminated by the classification section, and thus prevented from diminishing the crushing productivity of any particular bite. This makes the newly provided ability to adjust the gaps individually extremely valuable in keeping both bites working to full capacity. The value is illustrated by assuming that an operator notices that his coarse bite is not working to full capacity, but he can not increase the raw feed because the finer bite, already at full capacity, would then be overloaded. The solution this invention permits is to reduce the coarse gap. The coarse bite, crushing the same size input as before to a smaller size will now relieve the finer bite of some of its work, so that the raw feed can be increased without overloading it. One reason the separate adjustment of the coarse bite is so efi'eetive in reliev ing the finer bite of work is that a larger percentage of the discharge of the coarse gap will be fine enough to pass screen 37 and not have to go through the finer bite at all.

The use of the terms axle, shaft, and shaft means in connection with the crusher of this invention, is not intended to require a continuity between its ends. There could be two stub shafts each rigidly extending from an end of a roll.

I claim:

1. A crusher for rock and the like including a pair of spaced frame structures, a full width crusher roll means extending between and supported by the frame structures, a plurality of second roll means cooperating with the first roll means at angularly different positions about its axis, each of said second roll means being supported between and by said spaced frame structures with independent adjustment of its normal spacing from the first roll means characterized by:

said second roll means cooperating with axially different portions of the first roll means to form crusher bites so positioned that the crushed discharge from each bite is discharged from the crusher without passing through the other bite; and

means for separately feeding material to be crushed to each of the bites.

2. A crusher for rock and the like including a pair of spaced frame structures, a full width crusher roll means extending between and supported by the frame structures, a plurality of second roll means cooperating with the first roll means at angularly different positions about its axis, each of said second roll means being supported between and by said spaced frame structures with independent adjustment of its normal spacing from the first roll means characterized by:

said second roll means cooperating with axially different portions of the first roll means to form crusher bites so positioned that the crushed discharge from each bite is discharged from the crusher without passing through the other bite; and

means for separately feeding material to be crushed to each of the bites; and

means for screening and conveying the discharge from at least one of said bites and returning to the crusher such portion thereof as needs further crushing, together with screened material newly fed to'the crusher.

3. A crusher for rock and the like including a pair of spaced frame structures, a full width crusher roll means extending between and supported by the frame structures, a plurality of second roll means cooperating with the first roll means at angularly different positions about its axis, each of said second roll means being supported between and by said spaced frame structures with independent adjustment of its normal spacing from the first roll means characterized by:

said second roll means cooperating with axially different portions of the first roll means to form crusher bites so positioned that the crushed discharge from each bite is discharged from the crusher without passing through the other bite; and

means for separately feeding material to be crushed to each of the bites; and

means for screening and conveying the discharge from at least one of said bites and returning to the crusher such portion thereof as needs further crushing, together with screened material newly fed to the crusher, with selectivity by size in the delivery to each bite; whereby, when the bites are adjusted for different bite-spacings, coarser material will be crushed only by the coarser of the bites, and finer material only by the finer of the bites.

4. A crusher including:

a plurality of crusher roll axles being supported near the ends thereof;

support means for their support;

a first crushing roll means having a plurality of laterally arranged, adjacent, distinct crushing portions thereon, said first roll means being carried by one of said axles;

a plurality of second crushing roll means each being carried by a respective second axle, each of said second axles being individually supported to oppose one of said crushing portions with a normal spacing therebetween;

said axle support means including a plurality of bearing means for supporting the second axles with individual movement of each for varying its spacing from the first roll means;

means for movably supporting the bearing means, during said movement;

resilient biasing means for urging said second roll means toward the first roll means to provide the normal spacing; and

means for power rotating each of said rolls for downward movement of the surface thereof at the opposing areas.

5. A crusher for rock and the like including a pair of spaced frame structures, a full width crusher roll means extending between and supported by the frame structures, a plurality of second roll means cooperating with the first roll means at angularly different positions about its axis, each of said second roll means being supported between and by said spaced frame structures with independent adjustment of its normal spacing from the first roll means characterized by:

said second roll means cooperating with axially different portions of the first roll means to form first and second crusher at angularly different positions about its axis, each of said second roll means being supported between and by said spaced frame structures with independent adjustment of its normal spacing from the first roll means characterized by:

said second roll means cooperating with axially different portions of the first roll means to form crusher bites so positioned that the crushed discharge from each bite is discharged from the crusher without passing through the other bite;

means for separately feeding material to be crushed to each of the bites;

screen means cooperating with the means for separately feeding to feed coarser material to a first of said bites, and finer material, not reduced to size, to a second of said bites adjusted to smaller spacing than the first; the spacings of the first pair and second pair of crusher roll surfaces being independently adjusted for proportioning the crushing work between the two pairs in a manner to 5 keep both pairs substantially fully occupied;

conveying means for returning to the screen means for screening, with newly supplied material to be crushed, material which has passed through both bites; and discharge means for discharging from the screen means, without passage through either bite, screened material reduced to size.

6. A crusher for rock and the like including a pair of spaced frame structures, a full width crusher roll means extending between and supported by the frame structures, a plurality of second roll means cooperating with the first roll means at angularly different positions about its axis, each of said second roll means being supported between and by said spaced frame structures with independent adjustment of its normal spacing from the first roll means characterized by: I

sar second roll means cooperating with axially drfi'erent portions of the first roll means to form crusher bites so positioned that the crushed discharge from each bite is discharged from the crusher without passing through the other bite;

means for separately feeding material to be crushed to each of the bites;

screen means cooperating with the means for separately feeding to feed coarser material to a first of said bites, and finer material, not reduced to size, to a second of said bites adjusted to smaller spacing than the first; conveying means for returning to the screen means for screening, with newly supplied material to be crushed, material which has passed through both bites; and

discharge means for discharging from the screen means, without passage through either bite, screened material reduced to size.

7. A crusher for rock and the like including a pair of spaced frame structures, a full width crusher roll means extending between and supported by the frame structures, a plurality of 40 second roll means cooperating with the first roll means bites;

bearings for said roll means in each frame, at least one of the second roll means having a bearing adjacent to it in one frame and a bearing in the other frame spaced from it by approximately the axial length of the other second roll means, said bearings being movable toward and from the axis of the crusher roll and yieldably biased toward the crusher roll to normally maintain a predetermined spacing but to move back therefrom when a relatively uncrushable object passes between the rolls; and

coupling means for drivably coupling the said second roll means and the crusher roll, said coupling means having limited ability to maintain effective coupling in spite of yielding of the yieldable means, and being associated with the bearing which is more remote from its roll means and of which the yieldable means therefore yields least.

UNHED STATES PATENT @FMQE @ERHHQATE @f @QREUHQN P t N 3,647, 150 Dated March 7, 1972 Inventor(K) Rgy W. ste anek It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Front or Abstract page, inventors name, change "Stephanek" to "Stepanek" Column 2, at lines shown as 60 and 61, change "bearing" to "bearings"; after "which", change fis" to "are"; change "member to members".

Column 3, at line shown as 47, change "rock" to "cock".

Rewrite claims 5 and 7 as follows:

5. A crusher for rock and the like including a pair of spaced frame structures a full width crusher roll means ex tending between and supported by the frame structures, a plurality of second roll means cooperating with the first roll means at angularly different positions about its axis, each of said second roll means being supported between and by said spaced frame structures with independent adjustment 'of its normal spacing from the first roll means characterized by:

said second roll means cooperating with axially different portions of the first roll means to form first and second crusher bites;

bearings for said roll means in each frame, at least one of the second roll means having a bearing adjacent to it in one frame and a bearing in the other frame spaced from it byapproximately the axial length of the other second roll means, said bearings being movable toward and from the axis of the crusher roll and yieldably biased toward the crusher roll to normally maintain a predetermined spacing but to move back therefrom when a relatively uncrushable object passes between the rolls; and

coupling means for drivably coupling the said second roll means and the crusher roll, said coupling means having limited ability to maintain effective coupling in spite of yielding of FORM PO-105O (10-69) USCOMM-DC 60376-P69 U.S. GOVERNMENT PRINTING OFFICE: (969 O366334 UNHED STATES PATENT oTTTcT; @ER'ITKMQATE QT QQRRECTWN Patent No. 3 9 647 -5 D d March 7 1972 Inventor(s) Roy W. Stepanek,

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

[Claim 5 continued from page 1] the yieldable means, and being associated with the bearing which is more remote from its roll means and of which the yieldable means therefore yields least.

7. A crusher for rock and the like including a pair of spaced frame structures, a full width crusher roll means extending between and supported by the frame structures, a plurality of second roll means cooperating with the first roll means at angularl'y different positions about its axis, each of said second roll means being supported between and by said spaced frame structures with independent adjustment of its normal spacing from the first roll means characterized by:

said second roll means cooperating with axially different portions of the first roll means to form crusher bites so positioned that the crushed discharge from each bite is discharged from the crusher without passing through the other bite;

means for separately feeding material to be crushed to each of the bites;

screen means cooperating with the means for separately feeding to feed coarser material to a first of said bites and finer material, not reduced to size, to a second of said bites adjusted to smaller spacing than the first;

the spacings of the first pair and second pair of crusher roll surfaces being independently adjusted for proportioning the crushing work between the two pairs in a manner to keep both pairs substantially fully occupied;

conveying means for returning to the screen means for screening, with newly supplied material to be crushed, material which has passed through both bites; and

discharge means for discharging from the screen means, without passage through either bite, screened material reduced to size.

Signed and sealed this 5th day of December 1972.

(SEAL) Attest:

EDWARD MqFLETCHERflRg ROBERT G-OTI'SCHALK Attestins: Officer Commissioner of Patents 

1. A crusher for rock and the like including a pair of spaced frame structures, a full width crusher roll means extending between and supported by the frame structures, a plurality of second roll means cooperating with the first roll means at angularly different positions about its axis, each of said second roll means being supported between and by said spaced frame structures with independent adjustment of its normal spacing from the first roll means characterized by: said second roll means cooperating with axially different portions of the first roll means to form crusher bites so positioned that the crushed discharge from each bite is discharged from the crusher without passing through the other bite; and means for separately feeding material to be crushed to each of the bites.
 2. A crusher for rock and the like including a pair of spaced frame structures, a full width crusher roll means extending between and supported by the frame structures, a plurality of second roll means cooperating with the first roll means at angularly different positions about its axis, each of said second roll means being supported between and by said spaced frame structures with independent adjustment of its normal spacing from the first roll meanS characterized by: said second roll means cooperating with axially different portions of the first roll means to form crusher bites so positioned that the crushed discharge from each bite is discharged from the crusher without passing through the other bite; and means for separately feeding material to be crushed to each of the bites; and means for screening and conveying the discharge from at least one of said bites and returning to the crusher such portion thereof as needs further crushing, together with screened material newly fed to the crusher.
 3. A crusher for rock and the like including a pair of spaced frame structures, a full width crusher roll means extending between and supported by the frame structures, a plurality of second roll means cooperating with the first roll means at angularly different positions about its axis, each of said second roll means being supported between and by said spaced frame structures with independent adjustment of its normal spacing from the first roll means characterized by: said second roll means cooperating with axially different portions of the first roll means to form crusher bites so positioned that the crushed discharge from each bite is discharged from the crusher without passing through the other bite; and means for separately feeding material to be crushed to each of the bites; and means for screening and conveying the discharge from at least one of said bites and returning to the crusher such portion thereof as needs further crushing, together with screened material newly fed to the crusher, with selectivity by size in the delivery to each bite; whereby, when the bites are adjusted for different bite-spacings, coarser material will be crushed only by the coarser of the bites, and finer material only by the finer of the bites.
 4. A crusher including: a plurality of crusher roll axles being supported near the ends thereof; support means for their support; a first crushing roll means having a plurality of laterally arranged, adjacent, distinct crushing portions thereon, said first roll means being carried by one of said axles; a plurality of second crushing roll means each being carried by a respective second axle, each of said second axles being individually supported to oppose one of said crushing portions with a normal spacing therebetween; said axle support means including a plurality of bearing means for supporting the second axles with individual movement of each for varying its spacing from the first roll means; means for movably supporting the bearing means, during said movement; resilient biasing means for urging said second roll means toward the first roll means to provide the normal spacing; and means for power rotating each of said rolls for downward movement of the surface thereof at the opposing areas.
 5. A crusher for rock and the like including a pair of spaced frame structures, a full width crusher roll means extending between and supported by the frame structures, a plurality of second roll means cooperating with the first roll means at angularly different positions about its axis, each of said second roll means being supported between and by said spaced frame structures with independent adjustment of its normal spacing from the first roll means characterized by: said second roll means cooperating with axially different portions of the first roll means to form first and second crusher at angularly different positions about its axis, each of said second roll means being supported between and by said spaced frame structures with independent adjustment of its normal spacing from the first roll means characterized by: said second roll means cooperating with axially different portions of the first roll means to form crusher bites so positioned that the crushed discharge from each bite is discharged from the crusher without passing through the other bite; means for separately feeding material to be crushed to each of the biTes; screen means cooperating with the means for separately feeding to feed coarser material to a first of said bites, and finer material, not reduced to size, to a second of said bites adjusted to smaller spacing than the first; the spacings of the first pair and second pair of crusher roll surfaces being independently adjusted for proportioning the crushing work between the two pairs in a manner to keep both pairs substantially fully occupied; conveying means for returning to the screen means for screening, with newly supplied material to be crushed, material which has passed through both bites; and discharge means for discharging from the screen means, without passage through either bite, screened material reduced to size.
 6. A crusher for rock and the like including a pair of spaced frame structures, a full width crusher roll means extending between and supported by the frame structures, a plurality of second roll means cooperating with the first roll means at angularly different positions about its axis, each of said second roll means being supported between and by said spaced frame structures with independent adjustment of its normal spacing from the first roll means characterized by: said second roll means cooperating with axially different portions of the first roll means to form crusher bites so positioned that the crushed discharge from each bite is discharged from the crusher without passing through the other bite; means for separately feeding material to be crushed to each of the bites; screen means cooperating with the means for separately feeding to feed coarser material to a first of said bites, and finer material, not reduced to size, to a second of said bites adjusted to smaller spacing than the first; conveying means for returning to the screen means for screening, with newly supplied material to be crushed, material which has passed through both bites; and discharge means for discharging from the screen means, without passage through either bite, screened material reduced to size.
 7. A crusher for rock and the like including a pair of spaced frame structures, a full width crusher roll means extending between and supported by the frame structures, a plurality of second roll means cooperating with the first roll means bites; bearings for said roll means in each frame, at least one of the second roll means having a bearing adjacent to it in one frame and a bearing in the other frame spaced from it by approximately the axial length of the other second roll means, said bearings being movable toward and from the axis of the crusher roll and yieldably biased toward the crusher roll to normally maintain a predetermined spacing but to move back therefrom when a relatively uncrushable object passes between the rolls; and coupling means for drivably coupling the said second roll means and the crusher roll, said coupling means having limited ability to maintain effective coupling in spite of yielding of the yieldable means, and being associated with the bearing which is more remote from its roll means and of which the yieldable means therefore yields least. 